Sealed Connection For Fluid Conduit Parts

ABSTRACT

An assembly of fluid conduit parts is disclosed along with a method of assembling, a method of manufacturing and an apparatus for manufacturing the one of the fluid conduit parts. The assembly includes a blow molded part having a first portion. A second part includes a tapered section and a sealing flange extends from the first portion towards a central axis of the first portion at a distance, an end of the sealing flange defines an opening. The second part inserts into the opening and at least part of the tapered section is of a size larger than the opening. The sealing flange flexes upon insertion of the second part into the opening to define a contact surface between the tapered section and the sealing flange that extends around a perimeter of the tapered section where the sealing flange contacts the tapered section.

FIELD OF THE INVENTION

The following invention relates generally to blow molded parts and thecorresponding molds and methods for manufacturing the same. Moreparticularly the invention relates to a mold, method and blow moldedpart that provides improved sealing at a junction with another part.

BACKGROUND OF THE INVENTION

The use of blow-molding as a method for manufacturing various sorts ofarticles is generally well known. Typically, this process involves theuse of a mold consisting of two separate halves or portions havingcavities of particularly desired shapes and sizes. Usually, one extrudesa large-diameter, sealed tube of molten material (commonly referred toas a “parison”), places the tube between the mold halves, and closes themold around the tube. Fluid pressure is then introduced into the tube,forcing the molten tube against the walls of the cavities, conformingthe tube to the shape thereof. The pressure is maintained until themolten material cools and solidifies. The pressure is then released, themold halves are pulled apart, and the hardened article is ejectedtherefrom.

Before the blow molded part is removed from the mold, it is typicallyseparated from excess parison material called flash. This step can becompleted in-mold or can involve secondary operations. Typically, oncethe parison is extruded between the mold halves, it is pinched off atthe top and/or bottom and then blown into a part that takes the shape ofthe mold cavity. The pinch-off generates excess plastic material in theform of top and/or bottom flash.

Flash generation imposes limits on blow molding efficiency. In somecases, Flash removal is done with an in mold blade as shown anddescribed in U.S. Pat. Pub. No. 20130175739, the content of which isincorporated by reference herein.

Although the above referenced publication discusses various parts,systems, methods and/or features that can be used to the task of flashremoval in mold, in cases where the part is joined to another part, animproved seal is desired and therefore such improved parts, machineryand methods of manufacture are desired.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide improved in-moldcutting or punching techniques that control wall thickness and/or cutresidue in order to provide improved sealing between two parts.

It is further an object of the present invention to provide a mold andmethod for manufacture of parts with improved sealing features.

It is a further object of the present invention to provide parts thatsecurely and/or removably attach to another part to provide a reliableand lasting seal.

These and other objects are achieved by providing a twist lock blowmolded part and a second part having corresponding locking featureswhere the interface between the twist lock blow molded part and thesecond part includes an integrally formed cut residue that pushesagainst the second part when the twist lock and second parts are joinedand locked in place to provide improved sealing of the interface.

In one aspect an assembly of fluid conduit parts having a sealedconnection between the fluid conduit parts is provided and includes ablow molded part having a first portion. A second part includes an outersection which may be tapered. A sealing flange extends from the firstportion towards a central axis of the first portion at a distance, anend of the sealing flange defining an opening. The second part adaptedto insert into the opening and at least part of the tapered section of asize larger than the opening. The sealing flange flexing upon insertionof the second part into the opening to define a contact surface betweenthe outer section and the sealing flange such that the contact surfaceextends around a perimeter of the outer section where the sealing flangecontacts the outer section.

The distance may be measured from an inner surface of the blow moldedpart and is at least as large as a wall thickness of the blow moldedpart. A fluid dispensing portion may be connected to the first portion,the fluid dispensing portion including at least one hole such that thefluid can escape the blow molded part through the hole. In some cases amaximum pressure is defined as a maximum fluid pressure against thesealing flange that can be sustained by the sealing flange to preventfluid from exiting the blow molded part at the end, the fluid maygenerate a first pressure against the sealing flange, the first pressurehaving a first value and the at least one hole defining an escape area,the escape area sized such that the maximum pressure is greater than thefirst pressure. In some cases a lock may hold the blow molded part inplace when a fluid is introduced into the blow molded part such that apressure of the fluid presses against an inner surface of the sealingflange to thereby increase a sealing pressure between the contact areaand the tapered section. The second part may be a pipe. A channel may belocated between a first end of the first portion and another end of theblow molded part. A protrusion may be located on the second part andsized to fit in the channel such that the protrusion can move from afirst position towards a second position, where the first position iscloser to the first end than the second position. A catch may be locatedat an end of the channel such that when the protrusion is located at thesecond position, the blow molded part can be rotated relative to thesecond part to engage the protrusion against the catch. A notch may bedefined by the catch, the notch located between two peaks formed in theblow molded part such that upon rotation of blow molded part theprotrusion presses against one of the two peaks to thereby allow theprotrusion to advance past the one of the two peaks such that theprotrusion is located within the notch.

In another aspect a method of creating a sealed connection between twoparts is provided and includes one or more of the steps of: providing ablow molded part having a first portion with an inner surface and asealing flange extending a distance from the inner surface towards acenter of the first portion; providing a second part; inserting thesecond part into the first portion, the first portion having aninsertion point defining a radius in a range between a first radius andsecond radius where the first radius is defined by the inner surface atan end of the first portion and the second radius is equal to the firstradius minus the distance; deforming the flange upon insertion of thefirst portion towards the insertion point; locking the blow molded partin place such that the blow molded part remains stationary relative tothe second part when a fluid is introduced into the blow molded part.

The distance may be equal to or greater than a wall thickness of thefirst portion. A channel may be located between the end and another endof the blow molded part. A protrusion may be located on the second partand sized to fit in the channel. A catch may be located at an end of thechannel. The inserting step may include including moving the protrusionfrom a first position towards a second position, where the firstposition is closer to the end than the second position. The locking stepmay include rotating the blow molded part relative to the second part toengage the protrusion against the catch. The locking step may includeengaging the protrusion against a notch defined by the catch, the notchlocated between two peaks formed in the blow molded part such that uponrotation of blow molded part the protrusion presses against one of saidtwo peaks to thereby allow the protrusion to advance past the one ofsaid two peaks such that the protrusion is located within the notch. Thedeforming step may include deforming the flange such that an area ofcontact is created between the flange and an outer surface of the secondpart and the area of contact is annular.

In another aspect an apparatus for creating a blow molded part for afluid conduit assembly is provided and includes a mold having at leasttwo mold sections which when aligned at least partially define a moldcavity. Two mold blades are each movably disposed in one of the two moldsections. A portion of the mold cavity adjacent to the two mold bladesdefines an end of the mold cavity and the portion of the mold cavitydefines a first size aperture at the end of the mold cavity. The twomold blades define a second size aperture, the first size aperturelarger than the second size aperture to define a size difference betweenthe first and second size apertures where the size difference is greaterthan a desired wall thickness of the blow molded part.

The size difference may be at least two times the desired wallthickness. The two mold blades may be moved to cut the blow molded partcontained in the mold cavity, the cut forms a sealing flange thatextends towards a center of the first size aperture and is attached tothe blow molded part. A channel may extend from a first location towardsa second location wherein the first location is located closer to saidtwo mold blades than the second location. A recess at an end of thechannel may be located closer to the second location than the firstlocation and may intersect with the end of the channel. Two peaks may belocated on either side of a notch, the two peaks and notch formed in therecess such that a protrusion of a second part is retained within thenotch to secure the blow molded part to the second part.

In another aspect a method of manufacturing a blow molded part for afluid conduit assembly is provided and may include one or more of thesteps of: providing at least two mold sections each having a bladetherein, the at least two mold sections when aligned defining a moldcavity, the blades when aligned forming a blade aperture wherein an endof the mold cavity adjacent to the blades is larger than the bladeaperture by a distance greater than a desired wall thickness of the blowmolded part; expanding a parison against the mold cavity such that theparison is thins between the end and a cutting edge of the blade; andmoving at least one of the blades to cut the parison at the end.

The step of expanding may force the parison against the blade such thata local wall thickness of the blow molded part at the blade prior to themoving step is 50% or less of a desired wall thickness of the blowmolded part. In some cases the local wall thickness is 75% or less ofthe desired wall thickness. The desired wall thickness may beapproximately half a distance measured from a surface of the mold cavityat the end to the blade aperture. The blade aperture may be round. Atleast one of the at least two mold sections may include a channel and arecess, the channel extending from a first location towards a secondlocation wherein the first location is located closer to the blades thanthe second location, the recess at an end of the channel located closerto the second location than the first location and intersecting with theend of the channel. The expanding step may include expanding the parisonagainst the channel and recess such that an inner surface of the parisondefines a part channel and part recess corresponding to the channel andrecess of the at least one of the at least two mold sections.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an exemplary assembly including a blowmolded part according to the present disclosure.

FIGS. 2 and 3 are respectively bottom and front views of a blow moldedpart as shown in FIG. 1.

FIG. 4 is a side view of the blow molded part shown in FIG. 1.

FIGS. 5 and 6 are exploded and assembled cutaway views of the blowmolded part shown in FIG. 1.

FIGS. 7-9 show how assembly is performed for the exemplary assembly ofFIG. 1.

FIG. 10 is a perspective view of the blow molded part shown in FIG. 1.

FIG. 11 is a partial cutaway view of the assembly of FIG. 1.

FIG. 12 is an exploded view of a mold for manufacturing the blow moldedpart of FIG. 1.

FIG. 13A is a detail view of the mold of FIG. 12 which is used tomanufacture the blow molded part shown in FIG. 1.

FIG. 13B is a detail partial cutaway view of the blow molded part ofFIG. 1 shown during the molding process prior to movement of the blades.

FIGS. 14A-C are detail cutaway views of the sealed connection of FIG. 1.

FIG. 15 is a side view of the cutting blades of the mold shown in FIGS.12 and 13A and 13 B which is used to manufacture the blow molded partshown in FIG. 1.

FIG. 16 is a partial cutaway perspective view of a second exemplaryassembly including a blow molded part according to the presentdisclosure.

FIG. 17 is a perspective of the blow molded part assembly of FIG. 16.

FIGS. 18 and 19 show how the blow molded part assembly of FIG. 16 isassembled.

FIG. 20 is a top detail view of the blow molded part assembly of FIG.16.

FIG. 21 is a side detail view FIG. 18.

FIG. 22 is a partial cross section view of the blow molded part of FIG.16.

FIG. 23 is a top view of part of a mold for making the blow molded partof FIG. 16.

DETAILED DESCRIPTION OF THE INVENTION

In FIG. 1 a blow molded part 2 and a second part 4 (in this case awatering can) is shown. It is understood that the second part may alsobe blow molded. FIGS. 2 and 3 show additional views of the blow moldedpart 2. The blow molded part 2 secures to the second part 4 and createsan connection 6. The blow molded part has holes 8 at one of its end fordispensing of water and the connection 6 creates a seal between the blowmolded part 2 and the second part 4. As the part 2 is blow molded, itincludes a mold parting line extending from the end with connection 6towards the end with holes 8 therein. The parting line as shown includesboth straight and curved portions, with the straight portion closer tothe portion of the part having the connection 6 and sealing flange asdescribed herein. The mold parting line can also be further seen andunderstood from viewing e.g. FIGS. 12 and 13A which show the mold.

It is further understood that the second part may be made by otherprocesses, for example, the second part may be a brass, copper, iron,PEX or other type of pipe/pipe fitting. In one application, the blowmolded part 2 is arranged as a shower head such that household plumbingcan be used and a pipe or a fitting at the end of the pipe may includethe tapered section 146 and/or the protrusions 18 as described in moredetail below.

The outsides of channel 30′ and notch 22′ are shown in FIGS. 2 and 3.The inner sides of these structures allow for insertion and locking ofthe second part 4 to the blow molded part. The notch 22 may be providedon more than one circumferential location of the blow molded part 2 suchthat the blow molded part 2 may be rotated to different positionsrelative to the second part 4. For example, FIG. 1 shows the blow moldedpart 2 having a generally vertical surface 9, but the blow molded part 2in this case may be rotated around so that the surface 9 is atapproximately a 45 degree angle. Other positions and relative angles arepossible, depending on the orientation of the surface 9 relative to theaxis of the sealing region 5 and/or the angle of the spout 7 or pipe(not shown). Although FIG. 1 shows a watering can, it is understood thatthe features described herein could be applied to other water holding ordispensing devices such as showerheads or end caps for pipes.

FIG. 4 shows a side view of the blow molded part 2 and section line 5-5.FIG. 5 shows an exploded sectional view along section line 5-5 of theassembly shown in FIG. 1. The blow molded part 2 includes peak 20 oneither side of the notch 22. The protrusion 18 on the second part 4locks within the notch 22 once inserted into the channel and thenrotated as shown in FIGS. 7-9. Catch 24 retains protrusion 18 within thenotch to prevent axial movement of the blow molded part 2 relative tothe second part 4. FIG. 6 shows an assembled view of FIG. 5 and theprotrusion 18 is retained in the notch 22 between peaks 20/20′ andfurther retained by catch 24.

The process of locking the blow molded part 2 to the second part 4 isshown by FIGS. 7-9, where the parts are inserted together such that theprotrusions 18 align with the channels 30 and the blow molded part 2 isinserted 26 over the second part 4. The parts 2,4 are rotated relativeto each other 28 such that the protrusion travels over the peak 20/20′and is retained in the notch 22 and further retained by the catch 24.Connection 6 is created to seal the parts 2/4.

As shown in FIGS. 10, 11 and 14, in order to provide improved sealing, asealing flange 14 extends towards a center of the sealing portion 5towards central axis 110. This creates end surface 10, which is widerthan the wall thickness at the sealing portion 5. Upon insertion 26, thesealing flange 14 may bend from position 140 to 142 as the outer surfaceof the second part 4 progressively is inserted into the sealing portion5. Since the outer surface 400 may be tapered, the progressive insertionlikewise progressively bends the sealing flange 14 and provides pressurebetween the sealing flange 14 and the outer surface 400 which therebyimproves the seal of the connection 6. Further, when water pressure isintroduced through the parts 2/4, the water pressure although relievedby the holes 8 may also provide pressure against the inner surface 146of the sealing flange. This pressure would tend to press the sealingflange harder against the outer surface and thus provide a more leakresistant seal.

In FIGS. 12, 13A/B and 15, aspects of the mold used in making the blowmolded part are shown. Mold cavity 48 is formed upon joining moldsections 40 and 42. Reference protrusions/recesses 44/46 provide forproper alignment of the mold sections. Knives 50 are activated/movedwithin the mold by ram 52. As seen in FIG. 13A, the channel 54 and arecess 58 are defined within the mold cavity and the notch and peakstructures of the blow molded part are also provided by thecorresponding peak 56 and notch that are shown in the mold. Note thatthe notch is adjacent to the peak and the second mold half 42 includesthe opposite side of the notch/peak combination which thereby createsthe notch/peak 22/20 of the blow molded part 2.

In FIG. 13B, the blow molded part 2 is shown in the mold prior tocutting. The blade 50 and the corresponding blade on the other side ofthe mold are aligned such that the center of the blade aperture alignswith center 66. At the blade tip, the wall thickness 64 is less than thewall thickness 62. In some cases thickness 64 is 50% of thickness 62. Inother cases, 75%. It is understood that the thickness may range anywherefrom 90%-5%. This reduction in thickness creates the sealing flange 14and the movement of the blades severs the parison along a line 60 thataligns with the blade edge. Although in some figures, the sealing flange14 may have a constant thickness or a gradually reducing thickness.

In FIG. 14A the assembly is shown before part 4 is inserted into theblow molded part 2. FIG. 14B shows the assembly and FIG. 14C shows adetail view of FIG. 14B. As can be seen, sealing flange 14 is generallypointed downward in FIG. 14A (in this view) towards the central axis ofthe assembly. Protrusion 18 inserts along channel 30 in the blow moldedpart 2 and rotated 28 (as shown in FIG. 9) to engage the protrusion 18with catch 24. Upon insertion of the tapered section 146 causes thesealing flange 14 to bend and in some cases stretch inwards to createcontact surface 142 which has a width 140. This contact surface iscylindrical in that the sealing flange defines a round hole. It isunderstood that the contact surface could be annular in the sense thatthe tapered 146 and straight 144 sections may have other cross sectionalprofiles such as square, elliptical and others. In each case, regardlessof cross section, the sealing flange would extend into the openingbeyond the thickness of the wall (C). Due to the molding process shown,the sealing flange is created both by stretching over the blade andcutting of the blade. The blade initially thins the sealing flange mostof the way before cutting, and then upon cutting, there may be a pointedtip 148 or optionally a narrow flat surface at the tip 148 of thesealing flange. As can also be seen, the sealing flange rapidlyincreases in thickness when moving from the tip 148 towards inner corner150 of the blow molded part 2. This provides sufficient flexing suchthat the sealing flange bends easily while reducing the possibility ofplastic deformation of the sealing flange which would decrease thesealing pressure. Pressure such as water pressure is forced againstsurface 154 which increases sealing pressure at the sealing surface 142,which may in turn reduce gap 152 and increase the width 140 of contactsurface 142. When the blow molded part 2 is installed over part 4, theblow molded part is moved in a installation direction and the tip 148bends opposite the installation direction (or away from part 4) whilethe base of the sealing flange moves in the installation direction (orwith the blow molded part 2) thus causing the sealing flange to flex ina curved shape to form the gap 152 between stop 12 and the outer surfaceof the sealing flange. As shown, the sharpness of the curve in thesealing flange when installed progressively increases from the base 150towards the tip 148 due to the narrowing of the sealing flange from basetowards tip 148.

In FIG. 15, the end surface 10 and the sealing flange 14 of the blowmolded part 2 is shown. The distance (A) that the sealing flange 14extends from the inner wall of the blow molded part 2 is approximatelyequal to the wall thickness, for example, distance (B) is approximatelytwice or more distance (A). It is understood that depending on the taperof the outer surface 400 of the second part, the wall thickness of theblow molded part 2, the distance (A) may vary. For example, a steepertaper of outer surface 400 would result in less extension (A) of thesealing flange being necessary. A shallower taper would likewise requirelonger extension of the sealing flange.

Referring to FIGS. 16-23 a dishwasher 1 includes a feed tube 3 assemblyinstalled therein. The feed tube moves water to different locationswithin the dishwasher, for example to clean both the bottom and toptrays. For example, water spray bars 300, 300′ may rotate to distributewater and cleaning solution to aid in cleaning. The feed tube assembly 3may include a number of parts, including parts 2′ and 4′. One end 21′ ofpart 2′ may include the sealing flange 14′ which extends and tapersbeyond the inner wall at the end 21′. This sealing flange 14′ is similarto sealing flange 14 shown in the watering can example depicted in FIG.1.

Part 4′ is inserted 26′ into the opening of end 20′ and rotated 28′. Asshown in FIG. 21, part 2′ includes a catch 24′. As shown on the outerside of the part 2′ edge 24″ corresponds to catch 24′ and is located atan angle 210 with respect to perpendicular. This angle 210 of the catch24′ acts like a screw thread to cause a slight axial movement 29′ ofpart 4′ during rotation 28′ because protrusion 18′ is retained by thecatch 24′. This angle 210 and the axial movement 29′ may progressivelycompress or deform the sealing flange 14′ during coupling of the parts2′/4′.

A hose (not shown) may insert over end 204 and rings 200 may provideadditional sealing against the hose.

As shown in FIG. 22, a contact area 140′ is created between part 4′ andpart 2′ when assembled, which causes the sealing flange 14′ to deformslightly. The sealing flange 14′ may have a length equal to wallthickness C′ or greater than wall thickness C′ when measured from innersurface 160′.

Referring to FIG. 23, a detail of mold section 40′ is shown. This moldsection includes a moveable blade with two blade sections 50′ and 50″.Blade section 50′ extends into the mold cavity and operates in a similarmanner to blade 50 shown for example in FIG. 13A. Blade 50″ does notextend as far into the mold cavity as blade 50′ so that end 204 does notinclude sealing flanges and end 21′ does include sealing flanges.Depending on the desired configuration, it is also contemplated that ablade extending into the cavity as blade 50′ does could be substitutedfor 50″ to thereby create a blow molded part that would have two endsections 204/21′ having the sealing flanges. As shown in FIG. 23, therecess 202′ that creates the edge 24′ and catch 24″ is approximatelyperpendicular to the axis of end 21′. Depending on the desiredconfiguration, the assembly, recess 202′ could be angled to cause theaxial movement 29′ described herein.

It is contemplated that the location of the sealing flange could bereversed with respect to the two parts 2/4 such that the sealing flangewould extend outwardly from the part 4 and that tapering could be usedon the outer part. The protrusions, notches and channels describedherein may also be reversed with respect to parts 2/4 to create thelocking features described herein. It is also contemplated that theprotrusion and the sealing flange could extend from the same part,depending on the desired configuration.

Although the invention has been described with reference to a particulararrangement of parts, features and the like, these are not intended toexhaust all possible arrangements or features, and indeed many othermodifications and variations will be ascertainable to those of skill inthe art.

What is claimed is:
 1. An assembly of fluid conduit parts having asealed connection between the fluid conduit parts comprising: a firstblow molded part having a first portion; a second part including anouter section, the second part being blow molded; a sealing flangeextending from the first portion towards a central axis of the firstportion at a distance, an end of said sealing flange defining anopening; said second part adapted to insert into the opening in aninsertion direction and at least part of a tapered section of the secondpart has a size larger than the opening; said sealing flange flexing inthe insertion direction upon insertion of said second part into saidopening such that the end of said sealing flange moves inwardly in theinsertion direction and a contact surface is defined between the outersection and the sealing flange such that the contact surface extendsaround a perimeter of the outer section where the sealing flangecontacts the outer section; the flexing of the sealing flange caused bycontact between the contact surface and the tapered section; and a lockcomprised of a catch and a protrusion which interact with each otherwhen the sealing flange flexes and the contact surface and taperedsection are in contact, the lock holding the first and second parts inan axial position relative to each other.
 2. The assembly of claim 1wherein the distance is measured from an inner surface of the first blowmolded part and is at least as large as a wall thickness of the firstblow molded part.
 3. The assembly of claim 1 further comprising: a fluiddispensing portion connected to said first portion, said fluiddispensing portion including at least one hole such that the fluid canescape the first blow molded part through the hole.
 4. The assembly ofclaim 1 wherein at least part of the lock is located in an interiorsurface of the first blow molded part and another part of the lock islocated in an exterior surface of the second part.
 5. The assembly ofclaim 1 wherein the protrusion is located on the second part and thecatch is located on the first blow molded part.
 6. The assembly of claim5 further comprising a channel located adjacent the catch wherein theprotrusion fits within the channel.
 7. The assembly of claim 6 whereinthe channel is located between a first end of said first portion andanother end of the first blow molded part.
 8. The assembly of claim 6wherein the channel defines a notch located between peaks adjacent andon either side of the notch.
 9. The assembly of claim 1 wherein thecatch and protrusion are brought into interaction to hold the first andsecond parts in an axial position relative to each other at least inpart by rotation of the first blow molded part relative to the secondpart.
 10. The assembly of claim 1 wherein the first blow molded partfurther comprises: a mold parting line extending on the first portionfrom the sealing flange at a first end of the first blow molded parttowards a second end of the first blow molded part.
 11. The assembly ofclaim 1 wherein the second end of the first blow molded part has a fluiddispensing portion having one or more holes.
 12. The assembly of claim11 wherein the one or more holes are smaller than the opening of thefirst blow molded part.
 13. The assembly of claim 12 wherein the firstblow molded part and second part when assembled create a watering can.14. The assembly of claim 12 further comprising a dishwasher includingthe first blow molded part and second part when assembled together andto the dishwasher.
 15. The assembly of claim 1 wherein the sealingflange narrows in thickness from a base to a tip thereof.
 16. A blowmolded part having a sealing flange for a sealed connection between theblow molded part and a second part, the blow molded part comprising: afirst blow molded part having a body with a first portion at a first endof the first blow molded part; a sealing flange extending from the firstportion towards a central axis of the first portion at a distance, anend of said sealing flange defining an opening, the sealing flangenarrowing from a base to a tip thereof; said sealing flange configuredto flex such that an outer facing portion acts to create a ring shapedseal; a catch located between the first end and a second end of thefirst blow molded part, the catch spaced apart from the sealing flangeat a distance and defining a recess in an inner wall of the first blowmolded part; a mold parting line extending on the first portion from thesealing flange at the first end of the first blow molded part towardsthe second end.
 17. The blow molded part of claim 16 wherein the moldparting line is curved at least in part.
 18. The blow molded part ofclaim 17 wherein the mold parting line includes a straight section and acurved section.
 19. The assembly of claim 16 wherein the distance ismeasured from an inner surface of the first blow molded part and is atleast as large as a wall thickness of the first blow molded part.